The aurora borealis appears over Ice Camp Sargo as the sun sets during ICEX 2016.

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An Army paratrooper parachutes into the Arctic Circle during ICEX 2016.

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Hector Castillo, with Arctic Submarine Lab, works on a field expedition in the Arctic Circle during ICEX 2016.

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On March 2, the U.S. Navy kicked off a five-week exercise at the top of the world when it established Ice Camp Sargo on the Arctic ice.

More than 200 personnel from four nations are part of the exercise, dubbed ICEX 2016, which is designed to "research, test and evaluate operational capabilities in the Arctic region," according to a Navy press release.

"The Arctic environment plays a key role in national defense. With over a thousand miles of Arctic coastline, the U.S. has strong national security and homeland defense interests in the region," said Vice Adm. Joseph E. Tofalo, commander, Submarine Forces, which is leading the exercise.

ICEX 2016 is the latest of more than 26 Arctic exercises conducted by U.S. Submarine Forces since a U.S. submarine, the USS Skate, first broke through the ice at the North Pole in 1959.

Click through the gallery to see some of what's been happening on the Arctic ice this year.